Chuck



C. E. CLARK July 9, 1940.

CHUCKv Filed oct. 19,v 195s VN/VENTOR dar.; [dh/afd (Yayi ATToREYs the longitudinal distances between the gripping Patented July 9, 1940 CHUCK Charles Edward Clark, West Hartford, Conn., as-

signor to The Jacobs Manufacturing Company, Hartford, Conn., a corporation of Connecticut Application October 19, 1938, Serial No. 235,792

. 2 claims.

`This invention relates to improvements in chucks, of the type which depend upon the si multaneous rotation of a plurality of eccentric gripping jaws for engaging a tool. In order to make the jaws movable in such a way that the tool gripping parts of them can be moved into or close to a common axis so that they may grip tools of small diameter, it is necessaryto space such parts relatively on the several jaws to prevent them from interfering with one another. 'Ihis necessitates cutting away intermediate parts of the jaws and reduces their gripping areas. I-Ieretofore, such alternate gripping and cut-away parts of the jaws have been arranged normal to the axes of the jaws to form ribs which are rectangular in cross section. The gripping areas of such ribs are the same for different sizes of the tools which they engage, with the result that smaller tools are engaged by greaterv areas of the ribs than are required and larger tools by smaller areas than are required.

Another difficulty with former constructions is that the angularly spaced tool gripping parts of the jaws are so far apart longitudinally that there is a tendency to bend the tool and to make it run out of true.

The object of my invention is to overcome these objections and to provide a simple structure by which the tools are gripped more eft'ectively. This I accomplish by the simple expedient of tapering the projecting eccentric rib-like parts of the jaws longitudinally so that their parts which engage larger tools are wider than their parts which engage smaller tools. I also increase the width of the gripping areas of the ribs by making them in the form of helices of like pitch, with the projecting part of each helix disposed opposite the depressed portions of the two adjacent helices. By this arrangement the gripping areas of the jaws are increased and surfaces decreased.

I will describe an embodiment of my invention in the following specication and point out its novel features in appended claims.

Referring to the drawing:

Fig. 1 is a side elevation of a chuck which is made according to and embodies my invention;

Fig. 2 is a front elevation of the chuck shown in Fig. 1, with its front plate removed and with the clamping jaws in their inner position.;

Fig. 3 is a front elevation of the clamping jaws, showing them in full lines in their outer or most widely open position and in dotted lines in an intermediate position; and

Fig. 4 is a sectional elevation of two of the jaws, showing their intererelatedpositions. The section is taken on the line 4-4 ofFig. 2.

I designates the substantially lcylindrical body of a chuck having a transverse face II. This body has a tapered bore I2 at-its rear end which is adapted to iit a driven arbor in a machine tool,

such as a vpower drill. I3 is a sleeve rotatably supported on the body I0. At its front end is an internally toothed flange I4 which overlaps the outer face II of the body. The sleeve is biased to rotate on the body in an anticlockwise direction by a` spring I5. A suitable stop (not shown), is provided toy limit the relative rotation of the sleeve on the body in this direction. I6 designates posts projecting from the body I0. As shown, these are equally spaced angularly and from the axis of the bodyand are parallel with this axis. The outer ends of the posts pass through openings in a centrally perforated front plate I8 which is fastened to the body I by screws I9. Pinions I 'I which mesh with the gear on flange I4 are rotatively supported on the posts I6. These are somewhat wider than the flange so that they project beyond its outer surface.

20 designates the clamping jaws. Theseare rotatively supported on the posts I6 with interposed roller bearings 2|. Each clamping jaw is provided with a ring of short teeth 22 which engage the projecting parts of the pinions I1. The clamping jaws are held on the posts by the front plate I8.

The foregoing parts are but brieiiy described as they accord substantially with the construction more fully shown and described in the application for patent, Serial No. 218,111, filed by Arthur Merrick Stoner July 8, 1938.

My improvement resides in the novel construction of the clamping jaws. Inconimon with the clamping jaws shown in application Serial No. 218,111, these comprise bodies 23 having cylindrical bores 24 with eccentric portions 25 and spaced eccentric ribs 26 which terminate at edges 2"!,from which they are cut back, as at 2S (Fig. 2), to the parts of the body portions 23 which are nearest the axes ofthe bores. The parts 29 of the bodies which are between: the ribs are cylindrical, but curve outwardly, as at 29A, into the eccentric body portions 25 to increase the solid portions of the jaws and to shorten the ribs 26.

According to my invention, the ribs are tapered longitudinally and transversely. They are positioned helically and are of such a pitch that they parts 25 of the jaws.

The chuck may be easily operated while in rotation. A slight pressure of the hand on the sleeve I3 is suicient to move the jaws from their fully closed position shown` in Fig. 2 in a clockwise direction toward their fully opened position shown in full lines in Fig. 3. Then a tool is inserted and the hand released. The spring moves the jaws inwardly and the grip on the tool is instantaneous and self-tightening.

Structural modifications may be made within the scope and spirit of this invention. The entire eccentric portion of the gripping jaws, for example, may be formed of helical ribs projecting from a cylindrical body. Furthermore the advantage of tapering the ribs longitudinally may be retained with structures in which the ribs are normal to the axes of the jaws. I intend no limitations other than those imposed by the appended claims.

What I claim is:

1. A chuck of the character comprising a plurality of angularly spaced rotatively supportedchuck jaws having ribs extending eccentrically from said jaws in relatively staggered overlapping relations and forming gripping surfaces, said ribs being uniformly tapered in cross section to thereby make the area of their gripping surfaces greater at the portions thereof nearer the axes of rotation.

2. A chuck of the character comprising a plurality of angularly spaced, rotatively supported chuck jaws having helically disposed ribs extending eccentrically from said jaws in relatively staggered overlapping relations and forming gripping surfaces, said ribs being uniformly tapered in cross section to thereby make the area of their gripping surfaces greater at the portions Athereof nearer the axes of rotation, and the helical disposition of the ribs increasing the Width of the gripping surfaces.

CHARLES EDWARD CLARK. 

